1978
Mayor Edward I. Koch issues Executive Order No. 16, which formally establishes Inspectors General to monitor agencies throughout the City. The Order gives the DOI Commissioner responsibility to direct certain crucial activities of the Inspectors General, who were required to report on criminal and other significant matters to the DOI Commissioner.

1983
At Mayor Koch's request, DOI submits "Whistleblower" legislation to the City Council. The legislation, which was passed, afforded specific protection to City employees who report wrongdoing, corruption or criminal activity.

1984
DOI begins to review routinely some 7,000 financial disclosure reports filed each year with the City Clerk.

1986
Mayor Koch issues Executive Order No. 105, which places the Inspectors General Offices fully under the direction and control of the DOI Commissioner by integrating their personnel and resources into the structure of DOI.

1990
Section 31 of the revised City Charter takes effect, requiring that the appointment of the DOI Commissioner be made with the advice and consent of the City Council. A provision was also added to Section 801, which stated that to remove a DOI Commissioner, the Mayor had to file the reasons for the removal with the City Personnel Director, provide a copy of this rationale to the Commissioner and allow the Commissioner the opportunity to present a public explanation.

Susan E. Shepard is appointed first woman DOI Commissioner by Mayor David N. Dinkins and becomes first commissioner subject to the City Council's "advice and consent" requirement. Commissioner Shepard is a former Assistant U.S. Attorney and Chief Counsel to the New York State Investigation Commission.

As a result of budget cuts, Commissioner Shepard restructures the Department, reducing the number of Inspectors General from the 21 in 1990 to 14 in 1992.

The Office of the Special Commissioner of Investigation is created in response to growing public concern about corruption and misconduct in the New York City School District and was given a mandate to investigate criminal activity, unethical conduct, conflicts of interest, and other wrongdoing occurring within the school system. Edward F. Stancik is appointed to head the office.

1991
First comprehensive Investigative Policies and Procedures Manual is issued. Investigative Training Committee is established to promote the continuing education of the investigative staff.

1993
Howard Wilson, former Assistant U.S. Attorney for the Southern District of New York, is appointed DOI Commissioner by Mayor Rudolph Giuliani.

Rogues, Rascals, & Heroes, a history of the first 120 years of DOI, is published.

New York City Housing Authority Inspector General staff is brought under the supervision of the DOI Commissioner.

1995
As a result of the Mollen Commission hearings on police corruption, the Commission to Combat Police Corruption (CCPC) is created by Executive Order 95-18. The order directs the CCPC to work in tandem with the Department of Investigation.

Mayor Giuliani signs Local Law 50 to regulate the Fulton Fish Market, long acknowledged to be under the influence of organized crime. Subsequently, the Public Markets Unit is created within DOI to monitor activities at the fish market and at the City's other public markets.

1996
After a DOI investigation exposes abuses at the Central Punitive Segregation Unit on Rikers Island, 11 Correction officers are indicted by the Bronx District Attorney and the United States Attorney's Office for the Southern District of New York for use of excessive force. This investigation led to the settlement of a civil suit against the City of New York for $1.6 million. In 1998, the City entered into a Memorandum of Understanding with the Legal Aid Society that guaranteed DOI would monitor CPSU for wrongdoing, review penalties assessed to staff members for violating regulations, as well as perform background checks for all employees.

Edward J. Kuriansky, former New York State Deputy Attorney General for Medicaid Fraud, is appointed Commissioner by Mayor Giuliani.

1998
The Independent Private Sector Inspectors General (IPSIG) unit is added to DOI to insure contractor responsibility, especially in the construction industry.

1999
As DEP's responsibilities increase substantially following the 1997 Memorandum of Agreement for the New York City Watershed to protect the City's water supply, DOI opens an Office of the Inspector for the Department of Environmental Protection (DEP) in Valhalla, New York.